How much CO2 emission is too much?

This week, representatives from around the world will gather in Nairobi, Kenya for the latest Conference of Parties (COP) meeting of the Framework Convention of Climate Change (FCCC) which brought us the Kyoto Protocol. The Kyoto Protocol expires in 2012, and the task facing the current delegates is to negotiate a further 5-year extension. This is a gradual, negotiated, no doubt frustrating process. By way of getting our bearings, a reader asks the question, what should the ultimate goal be? How much CO2 emissions cutting would it take to truly avoid “dangerous human interference in the climate system”?

On the short term of the next few decades, the line between success and excess can be diagnosed from carbon fluxes on Earth today. Humankind is releasing CO2 at a rate of about 7 Gton C per year from fossil fuel combustion, with a further 2 Gton C per year from deforestation. Because the atmospheric CO2 concentration is higher than normal, the natural world is absorbing CO2 at a rate of about 2 or 2.5 Gton C per year into the land biosphere and into the oceans, for a total of about 5 Gton C per year. The CO2 concentration of the atmosphere is rising because of the 4 Gton C imbalance. If we were to cut emissions by about half, from a total of 9 down to about 4 Gton C per year, the CO2 concentration of the atmosphere would stop rising for awhile. That would be a stunning success, but the emission cuts contemplated by Kyoto were only a small step in this direction.

Eventually, the chemistry of the ocean would equilibrate with this new atmospheric pCO2 concentration of about 380 ppm (the current concentration), and its absorption of new CO2 would tail off. Presumably the land biosphere would also inhale its fill and stop absorbing more. How long can we expect to be able to continue our lessened emissions of 4 Gton C per year? The answer can be diagnosed from carbon cycle models. A range of carbon cycle models have been run for longer than the single-century timescale that is the focus of the IPCC and the FCCC negotiation process. The models include an ocean and often a terrestrial biosphere to absorb CO2, and sometimes chemical weathering (dissolution of rocks) on land and deposition of sediments in the ocean. The models tend to predict a maximum atmospheric CO2 inventory of about 50-70% of the total fossil fuel emission slug. Let’s call this quantity the peak airborne fraction, and assume it to be 60%.

The next piece of the equation is to define “dangerous climate change”. This is a bit of a guessing game, but 2°C has been proposed as a reasonable danger limit. This would be decidedly warmer than the Earth has been in millions of years, and warm enough to eventually raise sea level by tens of meters. A warming of 2° C could be accomplished by raising CO2 to 450 ppm and waiting a century or so, assuming a climate sensitivity of 3 °C for doubling CO2, a typical value from models and diagnosed from paleo-data. Of the 450 ppm, 170 ppm would be from fossil fuels (given an original natural pCO2 of 280 ppm). 170 ppm equals 340 Gton C, which divided by the peak airborne fraction of 60% yields a total emission slug of about 570 Gton C.

How much is 570 Gton C? We have already released about 300 Gton C, and the business-as-usual scenario projects 1600 Gton C total release by the year 2100. Avoiding dangerous climate change requires very deep cuts in CO2 emissions in the long term, something like 85% of business-as-usual averaged over the coming century. Put it this way and it sounds impossible. Another way to look at it, which doesn’t seem quite as intractable, is to say that the 200 Gton C that can still be “safely” emitted is roughly equivalent to the remaining traditional reserves of oil and natural gas. We could burn those until they’re gone, but declare an immediate moratorium on coal, and that would be OK, according to our defined danger limit of 2°C. A third perspective is that if we could limit emissions to 5 Gton C per year starting now, we could continue doing that for 250/5 = 50 years.

One final note: most of the climate change community, steered by Kyoto and IPCC, limit the scope of their consideration to the year 2100. By setting up the problem in this way, the calculation of a safe CO2 emission goes up by about 40%, because it takes about a century for the climate to fully respond to rising CO2. If CO2 emission continues up to the year 2100, then the warming in the year 2100 would only be about 60% of the “committed warming” from the CO2 concentration in 2100. This calculation seems rather callous, almost sneaky, given the inevitability of warming once the CO2 is released. I suspect that many in the community are not aware of this sneaky implication of restricting our attention to a relatively short time horizon.

Note: responding to suggestions in the comments, some of the numbers in the text above have been revised. November 7, 2:31 pm. David

232 Responses to “How much CO2 emission is too much?”

Re #96: (Sigh) We really need a forum for sensible discussion of economics. The poster gets into that economic fearmongering again (or is a victim of it), saying “It is not clear to me however, that governments should impose a quick starvation diet on society.” But there is no reason for such a diet. Just a couple of simple attitude changes could significantly reduce CO2 emissions within a decade: replace fossil-fuel generation plants with nuclear (and as much “alternative” as can be had); and place reasonable fuel economy standards on automobiles.

It’s ironic that you choose a citizen of India for your example, as models would typically weight the welfare of an Indian much lower than the welfare of someone in the rich world, on the assumption that the current distribution of capital must be optimal. Hence there is no obligation on the part of the rich world to mitigate externalities visited upon the rest.

Re 98

Arguing that we should ignore the discount rates and value of future consumption that are implied by the actions of real people (as studied by economists)

Most economists don’t study people. They study aggregate economic outcomes, then add the assumption that markets perfectly reflect individual preferences, and back out what preferences must be to make the observed world optimal. That’s circular. Subdisciplines that actually talk to real people have discovered huge gaps between theory and reality (surprise!). How many people do you thing would be indifferent to trading 20 units of their grandchild’s happiness for one of their own?

Re 102

You are confusing discounting welfare with discounting for the opportunity cost of capital. The former is an ethical choice. All sensible models – including those with 0 discount rates on welfare – do the latter. Most models also discount to account for the fact that future generations will be (hopefully) richer. A 0 discount rate on welfare does not imply foregoing all current consumption, nor need it be inconsistent with observed interest rates.

Ender Wiggen, Re #92 : You miss, or deliberately omit, the fact the the first commitment period of the Kyoto Protocol runs for only 5 years, from 2008 to 2012. Since the per capita emissions of the Annex I parties are many times higher than of those in the developing world, it makes sense that they start the process of reducing emissions, with other countries following suit in the next few decades.

Let’s put it this way. If the USA met it’s Kyoto commitments, its per capita emissions would still dwarf those of China, even through to 2050.

As for “severe restrictions” on Annex I parties. Well, I had to laugh. The restrictions under Kyoto are tiny, and easily achieveable with a modicum of effort. Our UK Government has hardly exerted itself, yet we have already surpassed our Kyoto commitment. The US economy is fabulously inefficient in its use of power and the marginal cost of abatement can easily be bourne by the world’s largest economy.

I fail to see how the US driving more fuel efficient cars, insulating its buildings more effectively and seriously investing in renewables and new nuclear build would export CO2 to China.

And finally (sorry for ramble) if the USA didn’t want to do ANYTHING it could still meet its commitment using the CDM to clear up Chinese Industry.

There is no excuse for non participation. UK GDP is up 40% on 1990 levels. Our emissions are down 15%. Do the math.

It’s a common Marxian misconception that economic growth in one place won’t benefit people in another. If you cut economic growth in the West, the poor countries will suffer badly. Why? Because it’s in the rich countries that state of the art innovation takes place. Where do you think nanotubes, robotics and artificial intelligence/dexterity will be developed, in Sierra Leone or the US? By strangling growth in the West you also strangle innovation. The fact that you haven’t seen this very obvious elementary economic fact in any mitigation strategy just shows that the strategies aren’t very realistic.

“If we have 50 years worth of business as usual development the costs impacts of climate change will dwarf the development gains we accure.”

Are you sure? 50 years of business as usual means nano-technology, carbon nanofibers, flywheel batteries, airships, robotics taken to a whole new level. Think a minute about what you can do with that technology.

Consider the following scenario: a factory that produces production robots is built in the sahara. These production robots mine the desert for minerals to build solar panels. These solar panels are in turn used to fuel more robots to build more factories to mine more minerals and build more solar panels. Give this process a few years and you have filled the Sahara desert with solar panels producing humongous amounts of electricity.

Consider another scenario: factories produce robots that produce water pumping equipment which are deployed with robots. These are then deployed in antarctica to pump up sea water on a massive scale, transporting it to inland antarctica where it is very, very cold and deposited. On a sufficient scale this could reverse sea level rise.

Consider a third scenario: robots again are built to purify salt water and transport it into deserts where robots plant trees and vegetation. In a few years of doing this all deserts in the world could be green, making them a humongous carbon sink. Consider just the Sahara which is 9 million km2. Assuming 17.7 kg C/m2 gives a total of 160 GtC stored in Sahara alone. Thus, the Sahara alone could be used to suck out 70 ppm CO2 from the air in no time.

All this would be insanely expensive today, of course, a real back breaker for the economy, but in 50 years it would cost at least 10 times less to do it, possibly a lot less, depending on how fast robotic and automation technology is developed, and then we would have between 5 and 10 billion rich people in the world to split the cost between as opposed to a mere 2 billion rich people today. In short, waiting 50 years and then solving the problem in one go — if indeed the scare turns out to be reality — will cost in the vicinity of 25-100 times less per capita than taking action today.

David,

many of the problems associated with CO2 is best solved with wealth. Indeed technology induced wealth solves both CO2-related problems AND all other sorts of nasty problems unrelated to CO2 such as poverty, disease, hunger, misery and disasters. By insisting on strangling economic growth, not only are you robbing the world of the best way to cope with climate change — technology — but also robbing the poor of the world the opportunity to cope with just about anything.

Me “If we have 50 years worth of business as usual development the costs impacts of climate change will dwarf the development gains we accure.”

Onar “Are you sure? 50 years of business as usual means nano-technology, carbon nanofibers, flywheel batteries, airships, robotics taken to a whole new level. Think a minute about what you can do with that technology. ”

Yes, Onar, I’m sure. Because those notable ‘Marxists’ at the International Energy Agency say so. There is no business as usual scenario in which fossil fuel use doesn’t massively increase on current levels, pushing atmospheric CO2 way beyond 550ppm. The resulting cost of climate impacts will outweigh any development gains made by the 3rd world. Don’t take my word for it, listen to another ‘Marxist’ (and former Chief Economist at the World Bank), Sir Nick Stern.

Consider this scenario : Mankind continues to burn increasingly large amounts of fossil fuels, which are cheap and in plentiful supply (whatever ‘peak oil’ types would have you believe). The factory that builds nanobots in the Sahara never gets built, because it was more expensive to build than to just keep burning fossil fuels. Then, suddely, we realise the earth is 3 degrees warmer than it was, the ice caps are melting and sub-Sahran Africa and Southern Asia are suffering from massive water shortages because of circulation changes. Pretty picture eh?

I simply don’t recognise your picture of CO2 controls OR ecomomic growth. It’s a false paradigm. I we spend between 1% and 3% of our GDP now on addressing this issue (and yup! A lot of that cash will be spent on developing the type of techical fixes you mention, and more besides) we will reap considerable economic benefits in the long run.

On the other hand, if we keep going the way we are going we WON’T see development in the third world. All the gains made will be washed away by the impacts of climate change.

One final note : You seem to be under the impression that once 3rd world countries make the ‘breakthrough’ their emissions will go down. Could you explain to me, therefore, why USA and Australia have the highest per capita emissions in the world (baring the Gulf States) and sub-Saharan Africa the lowest? And why, despite a booming economy, increasing oil prices and the near-limitless technological resources of the US Universities and National labs, US emissions are STILL RISING?

It means you space out consumption equally over time instead. Technically, my discount rate is actually negative since I seem perfectly willing to save with negative real interest rates (my estimates are that inflation is about 5% a year, and short term investments yield a little less than that).

Relying on future technological progress is a fool’s game. Most predictions turn out to be totally off, generally being overoptimistic. In the case of your robots idea, both capital and labor are in surplus throughout the world and have been since the Industrial Revolution. Robots would reduce labor costs, but when labor can be bought for a dollar a day, what’s the point? In fact, under a capitalist system, robots just serve to make the poor poorer, since there is even less demand for labor and that is the resource poor people have.

Technology is most likely to follow an S-curve, with innovation naturally trailing off. This has happened time and time again in virtually all individual fields, and it will happen at some point for technology in general (probably sooner than later, as even progress in computers appears to be slowing down).

With this in mind and considering that we only know what technology will be discovered after the fact, the best assumption is that in 100 years we will only have our current technology, probably better refined, to work with.

Re 103> …models would typically weight the welfare of an Indian much lower than the welfare of someone in the rich world…

I doubt that is the case. Do you have an example from a credible source?

>Most economists don’t study people. They study aggregate economic outcomes, then add the assumption that markets perfectly reflect individual preferences, and back out what preferences must be to make the observed world optimal. That’s circular.

Onar, you did not include the future of our commuting to work and the mall in our little Jetson jet-crafts.

You really let your imagination run wild. Try instead to imagine the impact of an ice-free Arctic on the precip and temp patterns of Western North American ag lands and what that would mean to the cost of grain on the world market. That is just for starters, Onar.

You sound like Sheik Mo of Dubai fame. He thinks palm islands are the way to go because he has the money to make that happen regardless of rising sea levels.

Can you please work out for us the weight of water and the average distance your robots would transport it to offset a sea level rise of 30cm. How much energy would that require? How many gallons/min need to be pumped to accomplish that over 100 years?

Until you have done some simple numbers like that you are just day dreaming a bad sci-fi novel.

I agree, but it seems some would like nothing more than to impose one on us.

By the way, the oil companies are not Gavin’s horses. It is the automobile (combustion horse) which is making the mess and emmitting the waste. The oil companies are the hay growers. It is not really the hay growers causing the maneur, but the horses. If one wants to stop the manuer, one might kill the horses first. Because we love our horse though, it may seem more palitable to instead kill the haygrower. But are we sure we won’t still need some hay after the horses starve? We better choose our victim wisely.

Coby, the answer to your question is approximately 2 million metric tons per minute or 35.000 tons per second. In order to achieve that you need 1.000 cables with a 6 meter diameter pumping at 1 m/s. Or it can be done with 36.000 cables with a 1 meter diameter pumping at 1 m/s. That’s doable even today.

Energy? Elevating 1 ton, say, up 1000 meters gives mgh=1000*10*1000= 10 million joules. Doing that at a rate of 35.000 tons/s gives 350 GigaWatts. Quite a bit, but doable even today. That’s approximately the amount of coal power plants China builds in 20 years.

The point is, doing something like this would suck today. It would be hard, and it would cost a lot. Now divide that cost by 25 to 100 and you have the cost per capita of doing it in 50 years. Much sweeter deal.

Thanks to all who replied, the answers were both sensible and helpful. After doing a little research on the topic I was surprised to discover that most of the talk about thermal pollution seems to be concerned with the Urban Heat Island (UHI) effect and the ongoing efforts to discount any bias that effect might have on land based instrument readings. Personally I’m satisfied that goal has been accomplished, but I would still be interested in a discussion of what, if any, contribution UHI’s and thermal pollution in general make to climate change, both locally and globally.

Purely by coincidence I was thumbing through a copy of the original 1972 edition of “The Limits to Growth” and they had a brief discussion of UHI’s. The example they used was the metropolis of Los Angeles, an area of roughly 4,000 sq. miles, which in 1970 had a localized UHI effect of about 5% of incoming solar. They projected this to increase to 15% by 2000 (hmmmm, wonder if they were right?).

They also stated that, due to the laws of thermodynamics, any energy used by humans that is not derived from incident solar must eventually be dissipated as waste heat, either directly or indirectly, so my original question about combustion alone was too narrow in scope. However, the point was made here that the total energy used by humans is several orders of magnitude less than incoming solar and therefore statistically insignificant in regards to global mean temperature (although it seems to be accepted that a contribution IS being made, however miniscule).

And yet I’m still left wondering: Aside from the question of global mean temperature, and granted UHI’s are by definition highly localized, even so, when you consider that the global population is growing by ~70 million per year and is becoming increasingly urbanized, isn’t it possible that taken together all UHI’s with an effect of 5 – 15% of incoming solar and covering 1000’s of sq. miles could collectively make a contribution to climate change?

In Oscar Wilde’s novel “The Picture of Dorian Grey,” the title character remains eternally youthful despite a dissipated life because his painted portrait, rather than he, suffers the ravages of time and corruption. At one point, his friend Henry Wotton remarks something along the lines of, “Ah, Dorian! I would do absolutely *anything* to recover my lost youth and vigor. Except, of course, diet and regular exercise.”

I sometimes have the impression that those who advocate leaving climate change problems to “market forces” will do absolutely anything to stave off the ravages of global warming — except, of course, reducing CO2 emissions and energy consumption.

you say you’re sure because some guys at some place say so? Well, I hear other economic experts that say completely otherwise. So, by your logic, I’m equally sure you’re wrong. I am sure you are wrong, but that’s because I’ve used my knowledge of economics, my reasoning and logic to consider the arguments myself, not because I listen to authorities.

“There is no business as usual scenario in which fossil fuel use doesn’t massively increase on current levels, pushing atmospheric CO2 way beyond 550ppm.”

When I participated in the review of the TAR what struck me was the complete and utter total lack of creativity in projecting new, innovative energy technologies. That’s of course nothing new. Have a peek at any scifi-movie from a few decades back and notice what a truly lousy job they do at predicting the future. The TAR is no exception. Basically its premise is that in 50 years we will still be producing electricity by boiling water, because that’s what we do today. Does that sound reasonable to you? How about fuel cells with 60% electrical efficiency? And what if someone invents the equivalent of a fuel cell for radioactive material? Bam! You double the electricity production from nuclear power plants. What about lighting? Today people use friggin 60-watt light bulbs. 20 years down the line they could possibly replace that by a 1 W laser or led based light. Imagine reducing the world’s lighting energy consumption by 80%! What about ultrastrong composites? Today a typical 767 airplane weighs some 30 tons. Built from nanotube composites it could weigh a mere 3 tons. Can you imagine the amount of energy that is saved by not having to lift 27 tons to 10 km altitude for every liftoff? Then there is flywheel energy storage for cars. Today a typical car has a total efficiency in the vicinity of 10%. With flywheels that can be raised to 80%. If the fuel is electricity from hydropower, the carbon emissions are zero. If the fuel is electricity from fuel cell based coal plants (60+% efficiency) then the total efficiency, including electricity production, becomes 50%. That’s an 80% reduction in carbon emissions from cars simply by switching from gasoline and internal combustion to fuel cell based coal power and flywheels. Not one of these technologies have been taken into account in the business as usual scenario.

“The resulting cost of climate impacts will outweigh any development gains made by the 3rd world.”

You sound awfully sure.

“Don’t take my word for it, listen to another ‘Marxist’ (and former Chief Economist at the World Bank), Sir Nick Stern.”

Well, he may be a Sir but he certainly doesn’t know much about economics and technological innovation. (His report has been totally bashed by other economists) The fact that he has risen to power in the World Bank says a whole lot about the World Bank.

“Consider this scenario : Mankind continues to burn increasingly large amounts of fossil fuels, which are cheap and in plentiful supply (whatever ‘peak oil’ types would have you believe).”

I’m with you. Peak oil doom is not very realistic.

“The factory that builds nanobots in the Sahara never gets built, because it was more expensive to build than to just keep burning fossil fuels. Then, suddely, we realise the earth is 3 degrees warmer than it was, the ice caps are melting and sub-Sahran Africa and Southern Asia are suffering from massive water shortages because of circulation changes. Pretty picture eh?”

First of all, we don’t “suddenly” realize that the Earth is 3 degrees warmer. We can monitor the Earth and its condition closely. Second, if we have the water pumping technology to reverse sea level rise and to green Sahara, then massive water shortages in Southern Asia doesn’t sound all that scary all of a sudden, now, does it?

The scenarios I pictured are examples of a technological safety net, an insurance plan just in case the whacko doomster scenarios really do turn out to be true. They don’t need to be put into action if not necessary, but if climate change is becoming a real nasty problem then we have the option of doing so. From an economic point of view this makes beautiful sense. The choice is between taking a major 100% certain blow to the economy NOW, rather than _maybe_ take a minor hit to a much richer economy in 50 years. From a rational point of view it’s no brainer. If you really care about the lives of billions of people on the planet then you step on the economic gas pedal and wait with action.

“One final note : You seem to be under the impression that once 3rd world countries make the ‘breakthrough’ their emissions will go down.”

Partly. China is today building coal power plants with 25% efficiency. Millions of chinese are *burning* coal in their stoves for heating and cooking. We’re talking less than 3% efficiency here. Transitioning to a more modern technology will no doubt also mean drastic improvements in energy efficiency. To put it another way: if China implemented ALL the technologies that I mentioned earlier then even at a US level of prosperity China would not consume more energy than today.

“And why, despite a booming economy, increasing oil prices and the near-limitless technological resources of the US Universities and National labs, US emissions are STILL RISING?”

Because as you say, historically the price of oil has been low. There has been little need for innovation in these areas. This does not mean that innovation is not taking place. Currently many of the energy technologies of the future are being conceived and developed in the US. If the greens had it their way in the 70s, that would not be happening right now.

“Most predictions turn out to be totally off, generally being overoptimistic.”

Really? My impression is that it is the other way around. Who overpredicted commercial airflight or even space travel 100 years ago?

“In fact, under a capitalist system, robots just serve to make the poor poorer, since there is even less demand for labor and that is the resource poor people have.”

Yet another Marxian misconception. Can you please explain why the wages are highest in the countries with the highest levels of automation and robotization? Increased productivity due to technology pushes real wages UP, not down. This is elementary economics.

“Technology is most likely to follow an S-curve, with innovation naturally trailing off. This has happened time and time again in virtually all individual fields, and it will happen at some point for technology in general (probably sooner than later, as even progress in computers appears to be slowing down).”

Really!? I would say that the fact that new fields and new technologies keep popping up is evidence to the contrary, namely that innovation is NOT slowing down. Why should it? Do you have *any* rational reason for why that should be the case?

Re #117:
“Yet another Marxian misconception. Can you please explain why the wages are highest in the countries with the highest levels of automation and robotization? Increased productivity due to technology pushes real wages UP, not down. This is elementary economics.”

“Really? My impression is that it is the other way around. Who overpredicted commercial airflight or even space travel 100 years ago?”

There were plenty of people in the 1960s who believed we would have space hotels today. People in 1999 believed that computers would keep doubling in performance every 1.5 years and that the effect would be revolutionary. Performance is now increasing at about half that rate, and the extra power has done little for us that 1999 computers couldn’t do). Or how about energy. Who would have predicted in 1990 that coal would be the energy source of the future (as it now appears to be, at least for the next few decades)?

In my lifespan, energy generation has barely changed. Oil, coal, and natural gas are still the source of 80% of our energy (as they were in the 1980s) and in the same pecking order no less. The very same gasoline still goes into Otto engines to fuel cars, which are about as inefficient as in the 1980s.

“Really!? I would say that the fact that new fields and new technologies keep popping up is evidence to the contrary, namely that innovation is NOT slowing down. Why should it? Do you have *any* rational reason for why that should be the case?”

I model technological innovation using a creaming curve – that easy inventions like the wheel and fire get invented first because they give a very big benefit and are fairly trivial to discover. As more things are discovered, the later discoveries are harder to make and give less benefit. Fusion power might be a nice technology to have, but the benefit will be less than going from animal power to steam power and it will be far harder to invent than the first steam engines were to invent. After fusion power, there exists only 1 possibly more efficient way to extract energy – black holes – and that is likely to remain in the realm of science fiction forever. At some point the cost of research will overcome economic growth and progress will stagnate.

Relying on technological progress to solve social problems just doesn’t work sometimes. Nuclear energy, after 50 or so years of commercial development, still hasn’t produced energy “too cheap to meter.” An overprediction. Airline tickets are still too expensive for most people, so many early predictions of widespread aviation (e.g. Stapledon in 1930) were overpredictions. “Cobalt bombs” never materialized, and neither did cold fusion, or solar power satellites, or O’Neill habitats in orbit, or nuclear rockets, or flying cars… want me to go on?

This is false. Higher wages encourage development of NEW technology, lower wages encourage implementation of OLD technology. So in China, where labor is cheap, they’re building bridges, roads and other old type technology to increase productivity, whereas in the US they’re developing internet commerce and nanotechnology to increase productivity. In both cases the result is automatization and capital accumulation, in both cases the result is increased productivity and therefore higher wages. Thus, automation drives up wages. That’s why we all are insanely rich today compared to 200 years ago.

“I model technological innovation using a creaming curve – that easy inventions like the wheel and fire get invented first because they give a very big benefit and are fairly trivial to discover.”

This is based on the false feudal assumption that wealth is a fixed quantity to be stolen, inherited or taxed, and that there is a fixed quantity of inventions out there in some platonic heaven to be discovered. Nothing could be further from the truth. Wealth is CREATED, not mined or stolen. Inventions are CREATED, not discovered. There is no end to the amount of inventions that is possible for humans. Why? Because new inventions lead to new possibilities, and new possibilities leads to the enabling of new inventions.

“As more things are discovered, the later discoveries are harder to make and give less benefit.”

How then do you explain the acceleration of inventions in human history? Fire was invented, what, 500.000 years ago? Then what? Stone tools some 40.000 years ago. Then what? Agriculture som 12.000 years ago when CO2 levels got high enough. Then what? Civilization some 4000 years ago. Then what? Capitalism some 250 years ago with steam power. Then trains, steel bridges, tall buildings, sanitation, cars, cargo ships, airplanes, electrical lighting, telephones, motion pictures, TV, plastics, computers, internet, mobile phones. Does that look like a slowing down of innovation to you? If later inventions give less benefit, why are new innovations popping up at an increasing rate?

Read up on the Negishi weights in the objective function of Nordhaus’ RICE model (you can also download the spreadsheet version and check the parameters yourself). The express purpose of the weights is to level the social ROI across regions; otherwise capital would immediately flow from rich to poor regions to equalize incomes everywhere. That’s fine to the extent that it captures the world order as it is; the US certainly isn’t about to give most of its GDP to the rest of the world, nor could it if it wanted to. However, when you then set policy using the same objective function, you are in effect saying that the universe has decided that people in China deserve to be poor, and who are we to stop them?

“How then do you explain the acceleration of inventions in human history?”

Two very powerful forces. First the discovery of writing allowed the storage of information (before that everything lived only in human minds, which meant that stuff was forgetten and reinvented quite routinely). Second, an enormous explosion in the human population.

Plot those inventions on a timeline and you’ll see no distinct pattern from 1850 to the present. Of the stuff you mentioned, 4 (computers, internet, television, and mobile phones) became important after 1950. Steel, trains, steam ships, and telegraphs (4 items) are in the 1850-1900 period, while the telephone, motion pictures, cars, airplanes, plastics, and electrical lighting (6 items) became important in the 1900-1950 period.

What is your alternative reason why agriculture wasn’t invented before the Holocene?

[Response:For that matter, I’ve sometimes wondered why agriculture wasn’t invented during the Eemian — the major interglacial before the present one, about 100,000 years ago. –raypierre]

[Response:Brian Fagan writes that agriculture was invented during the Younger Dryas. Humankind had gotten numerous enough through the Bolling, and dependent on gathering and storing wild stuff like acorns, that they were unable to just nomad away as they would have earlier. David. ]

“[N]ew inventions lead to new possibilities, and new possibilities leads to the enabling of new inventions.”

Also me:

“How then do you explain the acceleration of inventions in human history?”

You:

“Two very powerful forces. First the discovery of writing allowed the storage of information (before that everything lived only in human minds, which meant that stuff was forgetten and reinvented quite routinely). Second, an enormous explosion in the human population.”

So, basically you’re saying that one invention — writing — lead to new possibilities — storing vast amount of information — which enabled new inventions? If so, you’re saying exactly the same thing as I am. Now, generalize that statement from one invention to all inventions and you’re there. Every new invention enables several more. Thus, our possibility space is continuously growing, not shrinking.

“Plot those inventions on a timeline and you’ll see no distinct pattern from 1850 to the present.”

I beg to differ. Plot wealth creation on a time line from 1850 to present and you’ll see a very distinct pattern: exponential economic growth, implying accelerating innovation. The categories I mentioned after 1900 are extremely broad. Take “plastics” for instance. Is this really one innovation? Or is it a whole field of innovations that is still being explored to this day? I could name a few: rapid prototyping, flexible electronics. Then there are all the more mundane inventions: e.g. disposable cutlery and bags. Plastics is used everywhere in zillions of little devices and products.

“You believe that agriculture wasn’t invented earlier due to a lack of carbon dioxide?”

Well, duh! As I’m sure a lot of good climatologists here on RealClimate can tell you, summer temperatures, precipitation and stability in the sub-tropics were suitable for agriculture during the previous ice age. (This is where agriculture first emerged) Human intelligence reached its current levels in Eurasia some 30-40.000 years ago. Thus, the only limiting factor was CO2. You have to remember that during the previous ice age, CO2 was from a plant point of view at an all time low. Plants were literally starving and there’s just no way that plants below 200 ppm are remotely close to supporting agriculture. Thus, modern civilization owes its existence to this dreaded gas of horror and destruction, CO2.

the answer is intelligence. Eurasians didn’t achieve current levels of intelligence until some 30-40.000 years ago. Agriculture was dependent on a number of natural factors such as stable summer temperature, precipitation and CO2-fertilization, but it was first and foremost an intellectual achievement. The only thing missing in the previous interglacial was intelligence.

[Response: Intelligence is certain one possibility, but what is the actual evidence for any difference in intelligence 100K years ago? I suppose we know something from cave paintings, but that may be largely a matter of preservation and where people lived. Jared Diamond would probably have some alternate view, regarding the chance encounters of people and domesticatable animals and plants. –raypierre ]

Re #120 and “There is no end to the amount of inventions that is possible for humans. Why? Because new inventions lead to new possibilities, and new possibilities leads to the enabling of new inventions.”

The problem with this kind of reasoning is that, strictly applied, it predicts that there are no social problems — no pollution, no poverty, no climate change. Yes, technological invention is nice. No, it will not necessarily come along every time and save the day. There IS pollution, there IS poverty, there IS war, etc., etc., etc. Some of those problems have been made considerably worse by technology. You can’t really have a good system of concentration camps or labor camps if you don’t have railroads. And war can now involve taking out an entire city and surrounding area at a time, thanks to our friend, the atom.

This is one area where we (the RC “regulars”) might want to step back and take a more humble view.

There are lots of factors influencing the timing of the invention of agriculture. For example, 100,000 yr. ago humans probably didn’t have the technology for it. Our stone tools were far more crude then; I was surprised to learn from a PBS documentary that anthropologists refer to a time period 75,000 – 80,000 yr. ago as the “first great technological revolution” — a dramatic increase in the sophistication of stone tools. Also, agriculture benefits greatly from the domestication of animals, and that may have affected the timing. I have heard (although I can’t recall where) that agriculture was actually triggered by the evolution of new strains of cereal crops, which have a higher yield and greater food value for humans.

But this is just my speculation; I’m *certainly* not sufficiently well-informed to pontificate on the issue. I’d guess that none of those who posted “the reason” are sufficiently well-informed either.

There are a lot of “wicked smart” people here. This is the only discussion group I know of where a large fraction of regular *readers* have a long list of publications in the peer-reviewed scientific literature. But just because we’re wicked smart, that doesn’t mean we’re qualified to pronounce judgement outside our areas of expertise. I feel qualified to opine about mathematics, and to comment with some degree of expertise in physics or astronomy. I’ve also learned enough about climate science (from RC and other places) to comment intelligently on that topic — with caution and caveats. But the invention of agriculture? Get real.

You appear to believe that, at no time whatsoever should any restriction be placed on the combustion of fossil fuels. While these fuels are cheap and plentiful, we should continue to use them, whatever the cost.

If I am wrong on this assumption, please could you inform me of the circumstances under which such restrictions could come into place, and what such restrictions might be.

I’ve heard some very interesting “theories” [haha] about it, including that our hunter-gather ancestors lived in a time of plenty, and were forced to turn to agriculture when the climate deteriorated, such that the population numbers could no longer be supported by hunting and gathering alone.

Now Onar tells me that, in fact, the opposite is the case and that agriculture only became physically possible recently because of the bounty provided by an increase in CO2 levels.

You’ve further chipped in with an additional theory, that the transition was due to an internal technological and cultural dynamic independent of what we might call “external forcing”.

Now I know very little about what the evidence is for each of these competing theories, and not much more about the reasoning that behind them. How am I to distinguish between them?

Fortunately I don’t need to, because there is no consequence to whichever theory is most correct. I can relax and read about developments in New Scientist, Jared Diamond books, etc.

However, it strikes me that this is the situation many people find themselves in with regard to climate science and its warnings of major systemic impacts due to anthropogenic global warming. Is it due to CO2? Or simply the Sun? Or just part of some internal cycle?

I think everyone agrees that the answer matters a lot more than what the trigger was for the development of agriculture. How could you possibly decide, without learning about some of the details? Will people trust scientists, and their institutions, such as the IPCC and the Royal Society, enough in order to take mitigation actions on scientists say-so? Or, is it the responsibility of scientists to educate a majority of the people in the elementary facts of climate science, in order that action can be taken?

What might the “minimal crib-sheet” for climate science look like?

I don’t mean to sound overly dramatic, but it seems to me that this is a major challenge for the way that politics and science interact in the public sphere. You would hope that the general population would be educated enough that the comment pieces that maliciously misinterpret the science would simply be ridiculed and not get any traction. Sadly, this is not the case.

For a while now I have been wondering why there is little discussion about mitigation by breaking apart CO2. Though I see here ideas about dumping iron, are any more direct processes known?

I’m wondering whether to persue the topic, could anyone here let me know if the search is a waste of time?

What’s gnawing away at me is: We release CFCs and they end up breaking down ozone. Does anything otherwise benign happily break down CO2? Or is it a no – biological processes seem to be best at it, and they’re slow?

Boxes on every loungeroom or on every roof that just sit there pulling carbon from the air by breaking down CO2, where every few weeks you have to remove the block of carbon it creates. And something a lot faster at it than my potted plants.

I’m hoping someone could help me quickly dismiss these notions or point to forums on this subject? My guess so far is that such an angle isn’t promising enough to persue. I can find only disparate references to such ideas on the net, and they seem to involve things like furnaces.

It goes toward me understanding why the basic emphasis is on reducing emissions rather than negating them more directly. Thanks.

The nuclear capable-third world nations have created five miles-long nuclear waste-dump strips in the Pacific, below Japan.. and filled the area with much of their toxic wastes… Those crude nuclear piles are
boiling the water there, creating El Nino, changing the planet’s climate…

Diesel dust is attracting and holding the Sun’s heat in Arctic ice, is why the Arctic is crumbling, and is what those scientifically discovered “black rivers flowing under the Arctic ice” are…

When El Nino and diesel dust have melted the poles.. the planet’s weather will STALL.. and earth with turn into a dessert planet… Humanity goes extinct near the year 145,730AD.. when the last human can be seen cracking the marrow out of the bones of the second last…

When that massive nuclear pile in the Pacific goes critical, WE will have killed the Pacific.. and that will chain-reaction to kill all the seas…
A-men for the seas…

____________________

In topic “flying cars”…

I have the technology.. I can’t find the funding..?

1978 late Fall.. on a planned three-week leisurely cruise across Canada, along highway number-one, along as much of the scenic-routes as I could find.. just past the Ontario border into Manitoba.. I saw two large meteorites cross a huge “X” in the sky.. and thought about it with all I had.. “What makes Alien craft’s engines work”, I telepathed from all my Being, with all I had…
…A few minutes later, I had to park, to write the flood of new data, for three hours straight.. resulting in the crude bench manual to build a liquid electricity rocket…

James Watt watched a kettle boil, and invented a steam engine… I saw an X in the sky, and invented the liquid electricity engine…
I attempted to detail the workings of the engine to a visiting European nuclear physicist… 60-seconds into the description, his face when pale, his chin dropped, he struggled to speak, he accused me of “talking in the forth dimension”, barely managed to stand, managed to walk three paces, and fell flat on his face on the carpet…

Over the years I have contacted pretty-much every major scientific concern in the business world, to no avail…
All I got was classy snubbing and scorn from the mindless scientific community, governments, and religions… and a lot of remote viewers desperately trying to suck technology from my mind, mostly when I slept.. till I figured ways to seriously damage them upon approach… Plus there were a lot of attempts to dig into my computers, them believing I’d put the meat in a computer Not connected to the Net… They destroyed five PC’s… Seems this race doesn’t want engines for flying cars, and engines to take us to other solar systems… unless they can steal it from the inventor… It’s a pity I am being forced to take this technology to the grave…

All this engine is, is a couple serious modifications to laser… It cracks light… Damaged light-cones self-heal with the nearest molecules.. thus creating raw antimatter-acids, which are saved in exhaust scrubbers, and sold to power industry… The service station pays the consumer for plugged exhaust scrubbers.. A complete 180 turn around for having to pay for gas all these years…

Fragmented light-“particles” instantly decay into liquid electricity.. which, among 100 new technologies, in this science layer, replaces combustion as a power source, opens the bonds of the inert elements, establishes plazma welding of all materials to all materials, is the base to establish disintegrator trash-pails, obsoletes hospitals, gives us planetary defense weaponry, and thousands of new toys, and gets us to other habitable-planets before this one shows us we’ve already killed it…

It’s that.. or near the year 145,730AD, the last human is cracking the marrow out of the bones of the second last.. and by 155,000AD the planet can’t even support the life of a hardy beetle… I’m 59 now.. I don’t know how long I can hold all this data..? and I’m the only one who has it… I need use of a small lab, or this human race doesn’t get any of these technologies… I’ve taken it as far as I can.. the rest is up to this human race… If I hear no favorable response by my 60th birthday, the 75-thousand pages of notes burn in the garden, that evening.. and you’all can go try to find it all by yourselves, by your classic “scientific” trial and error methods…

If anyone has a clue how to get new technology funded, I’d sure appreciate hearing about it.. and I’m sure you would benefit from it greatly when I start marketing flying-cars…
Do you prefer two seaters or four seaters?..

Why is it so tough to get new technologies funded?.. Could it be that mankind’s intellect is devolving..? given that cell phones are baking brains, meth and coke are dissolving brains, the drug industry’s pain killers evolutions are numbing people to reality, dirty smallpox vaccinations are destroying brain file connections, and prolific lack of nutrients are literally desiccating brains…
Every day it seems more and more that humans are devolving into apes… Just look at how they, you, we, treat this planet…

________________
Thing is.. Diesel exhaust, as “lampblack”, is condensing to black rivers in the poles ice, and is melting the poles, while five seriously long nuclear waste dump strips, blow Japan, are boiling the sea bottom, creating El Nino, and will one day wonder “WHAT THE HELL HAPPENED TO OUR FUTURE?”… All we will know is that the melted Arctic rocks are all covered with a slippery fine black dust, which will make a useful black paint… And without the Arctic snow and ice hiding the rocks, the money suckers will find lots of gold and minerals to sell, while the planet is dying… We killed our planet!..

Bottom-line is, You get flying cars about five years after I gets a lab… Simple as that!… I’ve done a life-time of work acquiring this technology.. I’ve taken it as far as I can without funding…

So.. Now you know why you are not driving your flying-cars today.. and why those alive today won’t be seeing flying-cars in their lifetimes…

It won’t work with CO2 because it is more stable than any of the products it can be converted into (cyanide (CN), carbon monoxide (CO), carbon, nitrogen oxides (NOx), and oxygen are all less stable than CO2).

It makes sense considering how much energy one gets making the CO2 in the first place.

If it is proven that significant damage to individuals is caused when releasing more than some amount of CO2 into the atmosphere per year, then CO2 emissions must be considered a limited resource like any other resource and a system of private property for it developed. Property rights should be designated on previous emissions e.g. in the last 20 years. That is, if you emitted 1 ton per year for the past 20 years you own emission rights of 1 ton per year. You can do whatever you want with these emission rights, including selling them.

However, like in all cases of restrictions on people’s rights the burden of evidence is on the accuser. CO2 should be assumed innocent until proven guilty, and such a conviction should hold in court.

Re #116: You say “Today people use friggin 60-watt light bulbs. 20 years down the line they could possibly replace that by a 1 W laser or led based llight. Imagine reducing the world’s lighting energy consumption by 80%!”

20 years? You can get LED light bulbs today, though they’re a bit pricy. You can also get CFL bulbs that use maybe 10-15 watts to produce the same light as a 60-watt incandescent bulb. But because energy is artifically cheap, thoughtless people will use them to illuminate empty parking lots, floodlight their houses for “artistic” effects, leave them burning in broad daylight, etc.

Likewise, it’s possible to buy cars that get 70 mpg (there’s one sitting in my driveway); with existing technology it should be fairly easy to build one that gets 150 or more. (Or if you’ve got a spare $100K, you can buy a Tesla :-)) But because gasoline is artifically cheap, and because the automakers et al have persuaded the public that “status” depends on driving oversized gas guzzlers, most people choose not to buy the fuel efficient models.

That’s why improved technology alone is unlikely to do anything about CO2 and GW. People have to WANT to use it for that. Current technology can do the job, and without reducing overall prosperity, if the desire to act is there.

Yep. High school teaches science backwards — it’d be better to start with math, then physics, then chemistry, then biology, to give the basics needed to follow how photosynthesis works — and how much sunlight is available to drive photosynthesis (“primary productivity” — the basis of life on Earth) per year.

Photo: light; synthesis: chemistry — plants “sit there pulling carbon from the air by breaking down CO2, where every few weeks you have to remove the block of carbon it creates” — weeds and pond scum do it. But we’re burning fossil fuel far faster than photosynthesis is turning the CO2 back into solid carbon compounds, on a year by year basis worldwide.

there is evidence of a technological revolution during the previous ice age. This coincides with a pattern of skull size growth in Eurasians. Skull size, which is significantly correlated with intelligence, reached its modern level around 30-40.000 years ago. Thus, based on paleo-evidence Eurasian ancestors were as intelligent then as today. Thus, based on evidence of tool usage, cave art and skull size we can infer that Eurasians were mentally capable of inventing agriculture 30.000 years ago. Based on comparison with skull size variation in modern human races it is possible to infer that the rise in intelligence during the previous ice age was very significant making it highly unlikely that humans/hominids were capable of inventing agriculture in previous ice age cycles.

The climate in the southern parts of Eurasia was suitable for agriculture, even at the depths of the ice age. This leaves CO2-fertilization as the missing piece in the puzzle. Plants are generally very near extinction below 150 ppm, and at 180-190 ppm, which was the absolute low of the previous ice age, plants are highly unsuitable for agriculture as can be seen here. Full experiment here.

Curiously CO2-fertilization also plays an important role in the glaciation albedo feedback. Lower temperature leads to lower CO2-levels which leads to forest death which leads to glaciation southward advancement which leads to greater albedo which leads to lower temperature.

Thanks for this link, Gavin. I’ve been looking for a short “trial” summary like that.

If this were an actual trial the prosecution would have been thrown out of court.

1) When a murder takes place it is crucially important to be able to place the suspect at the scene of the crime at the time of the murder. Well, seems like CO2 can be placed at the scene of the crime, but only 800 years AFTER the murder. The prosecutions claim of time travel notwithstanding, this evidence does not hold up in court.

2) Milankovitch a co-conspirer you say? Doesn’t stand a chance in court. The problems with the theory are neatly summarized at Wikipedia.

3) The defence is capable of placing another suspect at the scene of the crime, and that is the sun. By extraordinary coincidence it turns out that the sun itself varies in a 100.000 year cycle which far better matches the ice age cycle than Milankovitch. This alone is sufficient evidence to get the case against CO2 thrown on its head out of court due to reasonable doubt.

But wait, the defence does not rest its case just yet. It is well known that solar magnetic activity is a good proxy for variation in TSI. This very real and uncontroversial forcing is not included in the prosecution’s calculation of forcings. Thus, we know for a fact 100% conclusively then that the climate sensitivity claimed by the prosecution must be too high on this account alone.

But wait, the defence is not finished. There is another possible solar mechanism connected with the variation in the magnetic field and that is the cosmic ray/solar indirect effect theory. This theory is currently controversial but evidence is mounting in the form of correlations on multiple time scales. Should this theory be confirmed by later experiments and findings the sensitivity may need to be reduced by a factor of 2,5-7,5, i.e. a climate sensitivity of 0,1-0,3 C/W. Incidently this is precisely the range of climate sensitivities you get from a host of direct measurements and calculations of the greenhouse effect. The only single piece of evidence pointing to a high climate sensitivity is the ice age evidence discussed in Hansen’s article. If it falls the whole climate bubble bursts.

Honestly, Gavin, with this evidence would you send a guy to the electric chair? I don’t think there is a judge in the world that would. In fact, I’m pretty sure a judge would say “come back in 15-20 years when or if you have a better case.”

[Response: I’ll bother with one of your points, – If you knew anything about what you were talking about, you’d know that the Sharma paper you allude to is not a measure of sun’s activity at all, but more a measure of changes in how isotopes get deposited over ice age cycles (correlation != causation remember?). Stretching this analogy further than it should be, note that this is a civil trial, not a criminal one, and the only sanctions that are being looked for are some amount of community service and possibly a cease and desist order. – gavin]

I read the abstract of Sharma’s paper. He himself warns (in the abstract, no less!) that some of the data may have been corrupted, therefore biasing the results, and that the study needs to be extended further back in time before results can be considered reliable (let alone conclusive). And if you know anything about time series analysis, you know that assigning any degree of reliability to the cause of a roughly 100000-yr. roughly periodic phenomenon based on 200000 yrs of data, is folly.

So, we have a very interesting theory but it’s based on far too short a time span, and there is reason to believe some of the data have been corrupted. At least, that’s what the author of the paper says.

But you seem willing to assign the cause of the ice ages to this new theory with certainty. Just as you seem certain that increasing CO2 concentration is the “cause” of the invention of agriculture, and to state that when CO2 levels are below about 150 ppm, plants are “very near extinction,” based on links to one experiment conducted on one type of plant. It seems to me that you have an illogical double standard.

By the way … references to material on the websites “junkscience” and “co2science” definitely detract from your credibility.

Peter Bellwood’s “The First Farmers” offers a most enjoyable survey of what is known about the origins of agriculture, including a bit of the stage known as proto-agriculture. However, Bellwood, nor others, take into account, at least not sufficiently, the much higher current sea stand. So all one can say with certainty is that proto-agriculture was practiced before Younger Drayas, without being able to state just how much before, at least near sea level rather than inland.

Some, probably including Diamond, have argued that agriculture requires a stable climate else the effort does not pay. The rest of the arguement is that this stabilty did not occur until the Holocene. Whether this argument is applicable to upland New Guinea has been questioned, with only a slightly (ca. 2 K) more variable climate during LGM.

One anthropologist, whose name I disremember, has argued that proto-agriculture and then agriculture was a reaction to the crowding which occurred as a result of the rising sea stand since LGM.

The arguments that agriculture cannot arise until a new toolkit is developed, or brain size is large enough, are of course reasonable. However absence of evidence is not evidence of absence. Raypierre’s suggestion that it was practiced in the Eemian is original, AFAIK. It might well have been so, on a small non-irrigated scale. If so, all the evidence is long gone or never looked for…

[Response: I wasn’t saying that agriculture was practiced in the Eemian, just that all the climatic factors generally invoked for the rise of agriculture were equally well in place at the Eemian. The one thing that’s uncertain is whether the Eemian had as stable a climate as the Holocene. –raypierre]

Onar (#138) “However, like in all cases of restrictions on people’s rights the burden of evidence is on the accused”. The right in discussion is the right to emit CO2.

Property rights, like the right to use your property to emit CO2, are not unlimited. Under the U.S. common law there is the legal concept “nuisance”, which has its basis in english law and has been part of the legal framework for hundreds of years.

Under nuisance, a person can not use their property in a way that interferes with another persons property rights. Polluting someone’s property has long been considered a nuisance. Nuisance is the legal basis for the current environmental law.
Wikipedia has a good articlehttp://en.wikipedia.org/wiki/Nuisance

There are mounting problems with the Milankovitch-theory. (summarized quite well in the Wikipedia article sited earlier). So much so that the ~100kyr (95kyr+120kyr+400kyr) eccentricity cycle in particular must be considered disproven. The final piece of evidence in this puzzle is the work by Muller and MacDonald showing that there is no evidence of a 95kyr, 120kyr or a 400kyr frequency in the climate data. There is only a very narrow 100 kyr frequency. This, taken together with the fact that the eccentricity cycle is the weakest of the Milankovitch-cycles, yet allegedly produces the greatest effect in terms of climate change, essentially disproves it as the driver of the ice ages.

Yet the extreme narrowness of the 100kyr frequency strongly points to an external, i.e. astronomical origin. It is very unlikely that internal climate dynamics could produce such a narrow modulation. Well then, we know that it’s not the eccentricity cycle, but it’s another astronomical cycle of some sort. Muller and Macdonald showed that there is a perfect correlation between the climate and the Earths orbital inclination, and postulated that interplanetary dust could be the driver, but currently this hypothesis is not supported by the evidence. This leaves the sun as the very obvious remaining candidate, and Sharma (and others) have produced evidence that the sun indeed has a 100kyr cycle.

Notice that the correlation between Be10 and O18 in Sharma02 *improves* when it is corrected for geomagnetic variation. This is strong evidence against a spurious correlation.

Maybe it’s just me but the balance of evidence is strongly tipping in favor of a solar explanation of the ice age cycle, and strongly in disfavor of a CO2-driven climate.

“Just as you seem certain that increasing CO2 concentration is the “cause” of the invention of agriculture, and to state that when CO2 levels are below about 150 ppm, plants are “very near extinction,” based on links to one experiment conducted on one type of plant.”

My link was by no means exhausting the evidence, just illustrating the problem with one particulaly visual experiment. There are literally hundreds of peer reviewed experiments that all confirm the same thing. C3 plants are generally highly unsuitable for agriculture at <200 ppm. If you don’t believe this you can always try to farm at 200 ppm. You will fail miserably, at least if feeding your family is the goal.

“By the way … references to material on the websites “junkscience” and “co2science” definitely detract from your credibility.”

I fail to see why, unless you judge arguments by who present them rather than by their merits. CO2science is to my knowledge the largest online repository of peer reviewed articles on CO2-fertilization, and the Idsos are experts in this field and highly recognized as such. As to junkscience.com, the essay I referenced is a summary of various calculations of climate sensitivity done by numerous researchers, all referenced. Could you please explain why you have problems with this?

10Be-concentration is influenced by precipitation, but 10Be-flux is not. Both correlate to climate change in the previous ice age, see. e.g. Van Geel et al.

Let me also add that in a rational society the trial would not be an analogy, but they way science interacted with politics. And even though it is a civil trial it is still required to provide actual hard evidence. And the stakes are very high here: the cost of mitigation will be approximately $30.000 per every full time worker. That’s not exactly nickles and dimes. In fact it corresponds to giving up approximately 1 full working year of your life. With severe economic punishments like that one better have the facts straight.

Re agriculture (and isn’t this getting a bit off-topic, interesting though it is?): I think some of us are asking and trying to answer the wrong question. Why should have early humans have bothered to invent agriculture, when their hunter-gatherer lifestyle provided everything they needed for less expenditure of effort?

As to the idea that a CO2 shortage restricted plant growth sufficiently to make agriculture impossible, what of the rest of the plant kingdom? The plants that humans cultivate are not fundamentally different from the rest of the plant kingdom, not even after some 10K years or so of selective breeding, and certainly not at the beginnings of agriculture. So if lack of CO2 restricted plant growth, we should see evidence of this in the fossil record: tree rings, pollen counts, and other such evidence of plant growth should show an obvious correlation to atmospheric CO2 levels as recorded in e.g. ice cores. I’ve never heard that it does, and I would expect to have seen the fact remarked on if it did.

Therefore I have to relegate this claim to the same category as most of the others made by the poster: wild theories made without supporting evidence for the purpose of obfuscation.